Hello,
It takes 20 working days to process the limited validity passport application in new delhi. you have to send all the supporting documents mentioned in the below link.
canadainternational.gc.ca/india-inde/new-ppts-for-children.aspx?lang=eng
In addition, you have to send pptc611 and pptc 445 forms as well.
If you are living abroad, you should submit all your originals of the supporting docs to the nearest Canadian embassy of that country.
Once you get the passport and If your child needs to travel to Canada with that passport, you need to submit the exit form at the immigration counter in the airport in india. The exit form can be obtained from district SP office.